A common question in the study of broadsword sources is how Scottish is the method of Roworth and Angelo? How much of it is merely labelled as Scottish, but in fact comes from elsewhere? It is quite fascinating to trace the development of this method over the course of the 18th century.
Angelo first published his “Hungarian and Highland Broadsword” in 1799, just shortly after Roworth published his “The Art of Defence on Foot, with the Broad Sword and Sabre: uniting the Scotch and Austrian Methods into one Regular System”.
Both these works followed the 1796 publication of “Rules and Regulations for the Sword Exercise of the Cavalry” by John Gaspard le Marchant, who spent a few years visiting and observing Austrian/Hungarian light cavalry. He brought back plenty of ideas about how to improve the British cavalry, and one of his noteworthy developments was the design of the 1796 pattern light cavalry sabre. His book was also the first British publication to include the cutting diagram of six numbered cuts, a device that Roworth copied wholesale in his book.
So we can see some central/eastern European influence coming into Angelo’s and Roworth’s works from le Marchant.
However, Roworth also plagiarised several sections from Thomas Page’s “The Use of the Broad Sword”, which was published in 1746. Page was an avid fencer who studied under Timothy Buck, who was a renowned gladiator and who ran a professional teaching establishment called the School the Noble Defence. So we can trace a strong “three kingdoms backsword” tradition (as Christopher Scott Thompson has called it) and lineage from Buck to Page to Roworth.
Angelo learned Highland singlestick from James Perry, a Highlander from Aberdeen who was in prison for libel, so there is also a traditional Scottish tradition that informed Angelo’s work.
Roworth studied at the Angelo School of Arms, and so there is quite clearly a giant mess of traditions and lineages and inputs that culminate in that method. Quite importantly, though, there is definitely some Scottishness and Highlandness somewhere in that melting pot of systems.
A good question for further discussion would be exactly which parts of the system are Scottish, and which parts are imported from elsewhere. But, to answer the question posted at the start of this article, we can trace some Scottishness at the very least in the method of Roworth and Angelo, so the mention of the Highlanders was not entirely a marketing ploy.
For a more thorough and detailed treatment of the question, please refer to my book Scottish Broadsword and British Singlestick, available from my website and from Fallen Rook Publishing.
Useful reading material
Angelo, Henry; Ben Kerr and Keith Farrell (eds.). The Guards and Lessons of the Highland Broadsword, 1799. Glasgow: Fallen Rook Publishing, October 2014. ISBN 978-0-9926735-3-6.
Farrell, Keith. Scottish Broadsword and British Singlestick. Glasgow: Fallen Rook Publishing, October 2014. ISBN 978-0-9926735-1-2.
Roworth, Charles; Ben Kerr and Keith Farrell (eds.). The Art of Defence on Foot, 1798. Glasgow: Fallen Rook Publishing, October 2014. ISBN 978-0-9926735-2-9.

Keith Farrell teaches HEMA professionally, often at international events (why not hire me to teach at your event?), and has an interest in coaching instructors to become better teachers. I teach regularly at Liverpool HEMA, and help behind the scenes with running HEMA in Glasgow at the Vanguard Centre.
I have authored Scottish Broadsword and British Singlestick and the award-winning AHA German Longsword Study Guide, and maintain a blog at www.keithfarrell.net where I post regularly.